Tuning indicator device



April 20, 1943.

A. T. VOSSEN 2,316,916

TUNING INDICATOR DEVICE Filed Feb. 29, 1940 /4m /6m 2001 '1 25m 30mTUNING ll'l l'l l'l l'l l'll pm 30m l' I BANDSPREAD L DIAL 2 BANDSPREADINVENTOR'. ARNOLD 72 l/OSSEN A TTORNE Y.

UNITED STATES PATENT OFFICE TUNING INDICATOR DEVICE Arnold '1. Vossen,Eindhoven, Netherlands, assignor to Radio Corporation of America, acorporation of Delaware Application February 29, 1940, Serial No.321,412

In the Netherlands July 29, 1939 3 Claims.

This invention relates to a wireless receiving set comprising a coarseand a fine adjustment center of the wave band associated with each ofthese stations.

tuning device, the latter permitting of spreading Now, the invention hasfor its object to prowave bands. This so-called band spreading is vide adevice enabling the user of the wireless primarily used in theshort-wave region in which 5 receiving set to effect accurate tuning toa given the stations are assembled in a number of wave po nt in a waveband, for exampl to the center bands and in which the stations comprisedin the of the wave band, by means of the coarse adsame band are closelyadjacent each other on justment tuning device. A wireless receiving setthe tuning dial. Generally, the same tuning according to the inventionis haracterized in that member as that by means of which the long andthe attainment of that given point in a wave band medium wave ranges areattended also serves to in which tuning to a given wave length has to becover the short-wave range but in this latter ffected by means of thefine adjustment tuning range due to the stations being in closeproxdevice is m k w y a lling device 01 imity to each other it is verydiflicult to tune to Hating y Optical meansany station comprised in anyof the bands by In one embodiment of the invention th movm ans of thistuning member which as regards able part of the coarse adjustment tuningdevice this range is of coarse adjustment. Now, by using has coupled toit one or more contacts adap ed band spreading, that is to say bypassing over to cooperate with one or more contacts arranged from thecoarse adjustment tuning device to a in the set in a stationary manner,the arr n fine adjustment tuning device, it is nevertheless ment beingsuch that upon attainment of a given possible to tune the set readilyand to a sufpoint, e. g., th center of a wave band capable ficientlyaccurate extent to the short wave staof being spread by means of thefine adjustment tions. According to a well known method of band tuningdevice, an electrical circuit is opened or spreading a small variablecondenser is connectclosed so that the signalling device is set into edin parallel with each of the tuning circuits. operation. As mentionedbefore, the coarse ad- As an alternative, band spreading may beobjustment tuning device may be constituted either tained by means of avariable inductance inby a variable inductance or by a condenser.Accluded in'each of the tuning circuits. In the cording to theinvention, when use is made in said cases the coarse adjustment tuningdevice the wireless receiving set of a variable condenser may beconstituted either by a tuning condenser which may be either a rotarycondenser or a or by a variable inductance. sliding-electrode condenser,the movable contacts In order that it may be possible to tune the setmay be coupled to the shaft of the condenser.

by means of the fine adjustment tuning device to According to theinvention, the wireless receiva station comprised in any of the wavebands ing set may be constructed in various ways. In to be spread it istherefore sufficient to tune in one embodiment of the invention onecontact for to the proximity of the station by means of the each waveband is arranged so as to be stationcoarse adjustment tuning device,after which acary relatively to the shaft of the coarse adjustcuratetuning to the station can be attained by ment tuning device, saidcontact cooperating with means of the fine adjustment tuning device. asingle contact arranged in the set in a station- Since for the purposeof tuning to a short wave ary manner. It is, however, also possible forstation the user of the wireless receiving set genthe contactsassociated with the wave bands to be erally disposes of a tuning dialassociated with arranged in the set in a stationary manner and the fineadjustment tuning device it is essential to cause them to cooperate withone contact arin order to enable continuous use of this dial that rangedin a stationary manner in relation to the the adjustment of the fineadjustment tuning de- 4 shaft of the coarse adjustment tuning device.

vice should always be identical whenever tuning In a further embodimentof the invention the is effected to the said station. This means thatcontacts cooperating with each other may be conin this case it is alsonecessary that the coarse stituted by a pair of contacts on the one handadjustment tuning device should always effect the and a single contacton the other hand. The same adjustment when the set is being tuned tonature of the cooperation depends on the conthe same station. This alsoapplies to the other struction and the arrangement of the saidconstations comprised in the various wave bands. tacts. The constructionand the arran It is customary to choose the adjustment or the may besuch, for example, that when the coarse coarse adjustment tuning devicefor each of the adjustment tuning device; is tuned to the center shortwave stations So as to coincide with the 0f a wave band the two contactsof the pair of this case they are adapted to cooperate with the contactarranged in the set in a stationary manner. It is also possible toprovide a single con.- tact for each wave band to be spread, thecontacts being in this case adapted to cooperate with one pair ofcontacts. In this case, the pair of contacts may, as before, be coupledsimilarly to the method hereinbefore described; forthepairs of contacts,to the movable part of the. tuning member or they may be arranged in thesetina stationary manner. The same remark applies to the contactscpcretinew h re n ice tacts. 7

According to the invention, wherg-the. .vwireless receivingset isfurnished with Va rotary con denser that acts as the; coarse adjustmenttuningdevice the sha ft of thc ,rotarycondenser. may carry a discordrum; which, on itsperiphery, carries. a pairof; contacts for eachofthe wave bands to bespread; a contact-arranged in the set in astationary-manner bearing on the periphery of the disc or; drum, thearrangement being such that'when the; condenser is tuned, for; example,to the center-oi a wave. band the contact-s of the pair of contactsassociated-with this wave band are shun b h con ac arranged he cti a,stationary 1 18621151..

A suiable; o ica i al in .dc iccmeyrb c taincd y. eans f: on r moreources of. i i t on. The si na which se v n. 11911; ettainment of a ivnpo n n awar hammer be the sudden illumination or theextinguishment ofvan incandescent lamp, the sim ltaneous operation: of; two lamps,.cthcrno sib itic e ng. 2 precluded;

Acccrdine'tc. the in ntion, in t ast d c ssed fcrm of c nstructio of; awir e s r ceiving set according to the invention, in which consequentlya dis r drum. arr s airs. o contactsequalin number to thenumber of wavebands. to, be spread and; capable of cooperating successively With a.contact ar an ed iihe s in a stationary manner, the signalling devicemay be constructed as.fo1lQW f the 99m? arranged in the set in astationary manner is y c ed t on of th contacts c Pa r of contacts, anelectrical circuit is closed which includes a source ofilluminationgiving oii a given color, and if the contact arranged in theset in astationary manner is only connected to the other contactof thepair of contacts a circuit is closed which includes a source ofillumination emitting the complementary color ofthe color of thefirst-mentioned source of light, whereas in the case of the pair ofcontactsbeing shunted by the contact arranged in the set in a stationarymanner both circuits are closed.

If one of the sources of light gives off, for example, red light and theother source of illumination green light, both sources of lightwill giveoff light in the case of both contacts of a pair of contacts beingshunted by the contact arranged in the set in a stationary manner. Ifthe light of both sources of illumination is thrown on to a screen thiswill be illuminated white.

In one preferred embodiment of the wireless receiving set according tothe invention a contact cooperating with a pair of contacts and adaptedto move relatively thereto cooperates when the coarse adjustment tuningdevice has arrived at one end of a wave band, with one of. the ends,remote from each other, of the contacts of this pair of contacts. In theembodiment described hereinbefore one of the sources of light, forexample the red one, will operate upon a wave band being entered into,whereas this source of illumination extinguishes on the Wave band beingleft on the same side. The entering into or leaving of the wave band onthe other side results in the other source of illumination, inthisinstance consequently the green one, starting to operate orextinguishing respec- In order that the invention may be clearlyunderstocd and readily carried into effect it will now be described morefully with reference to the accompanying drawing, in which F .1- 1; htwo i ad al' t e w re e s receiving set comprising a coarse.- and. afine ad.- justment tuning device Fig 2 shows a tuning circuit of thewireless receiving set.

Figs. 3 and 4 show two different positions. of the. condenser shaftwhich has coupled tolfit a number of pairs of contacts adaptedtocooperate with a contact arranged in the, setina. stationary manner.

Fig. 5 diagrammatically shows thecontact clevice and the signallingdevice,attendedtherebyl Figs, 6A, B, Cand Q showlvarlious positions ofth ccn aci a r d n h e n" a s t a manner relativelyto-a pair of.cofitactfsfconpled tcith e condenser shaft.

Big 7 diagrammaticallyshows a part of. the signalling-device. 7 L 1 Thetuning dial I shown in, Fig, 1 comprises five waye bands'viz. the 14meter, 16. met-trim meter. time}: @nd' 3Q fi an s, her of s ati ns say 21' cmb d iii cash he e band f ew fc e ema. air.- rangement-of thestations onthe' tuning dial it is very difficult to tune'to a s'tationcomprised in any-of the. wave bands in a manner similar to that; adoptedin the'medium' or long wave'ba'nd. This difficulty issolved by theuseofbandspread ing, One manner of bandspreading'fi i illustrated inFig. 2. In this? figure L ne or the timing circuits of the wirelessreceiving set is shown to be built up from an inductance Lja variablecondenser C, which generally also serves for. tuning in the medium an dlong wave bands,and. a condenser C which is connected in parallel with.thiscondenser and is small. compared therewith.

The condenser 0 permits of covering the entire tuning dial I, and thecondenser C of covering only a small part, but with substantiallygreater accuracy since in the caseoi equal deviations of the movableparts of the condensers the can denser C submits the tuning circuit to asubstantially smaller variation in capacity than in the case of thecondenser C. Thus a tuning dial may be provided for each wave bandwhich. is substantially larger than the wavel'b'and. Such a tuning dialis shown in Fig. l for. the 39 meter band and designated by 2. The otherspread wave bands may also be arranged on this dial but it is alsopossible to use aseparate f tuning dial for each spread wave band. rnners a given station lying, for example, in the. 301 neter band thefollowingprocess is adopted. By means of the tuning condenser C the setis tuned to the wave band that contains the desired station. Since thetuning dial 2 is rated at a given tuning of the condenser C in the waveband it is necessary for enabling the tuning dial 2 to be used that thecondenser C should be retuned accurately to the same point in the waveband. Generally, the center of the wave band is taken for such point.Next, by means of the fine adjustment condenser C the set can be tunedto the desired station which is indicated on the tuning dial 2. If,however, the condenser C were tuned slightly to the side of the correcttuning position in the wave band, the desired station, if it can bereceived at all, will not longer coincide with the indication on thetuning dial 2.

According to the invention, in order to enable the user of the wirelessreceiving set to tune the coarse adjustment tuning device, that is tosay the condenser C in the case discussed here, correctly in an easy andaccurate manner, provision is made of a signalling device one form ofconstruction of which will be set out by reference to the Figs. 3, 4, 5,6' and '7.

The shaft 3 (Figs. 3 and 4) of the rotary condenser, which isconstructed as a coarse adjustment tuning device, has fast on it aninsulating disc 4 carrying at its periphery five pairs of contacts eachcomprising the contacts a and b. These pairs of contacts are designatedby Mm, I6m, 23m, 25m and 30m. A contact 5 constructed as a rollersupported in the carrier 6 is mounted. in the set in a stationarymanner. This roller is forced into contact with the periphery of thedisc 4 by a compression spring I. The pairs of contacts I4, I5, 20, 25and 30 are distributed in such manner along the circumference of thedisc 4 that when they cooperate with the contact roller 5 the set istuned in the I4 meter, I6 meter, meter, meter and meter bandsrespectively. The contacts a and b of each pair of contacts constitutethe limbs of a V which in this form of construction form a very obtuseangle with each other. In Fig. 6 several positions of the contact roller5 relative to the disc and one pair of contacts a, b are showndiagrammatically, said positions being successively obtained whenin Fig.3 the condenser shaft 3 is rotated in the direction shown by the arrow.In Fig. 6A and also in Fig. 3 the roller 5 bears on the circumference ofthe disc 4. In Fig. 6B the roller 5 has engaged the contact I). In Fig.6C, similarly to Fig. 4, the roller 5 is connected to both contacts aand b, whereas in Fig. 6D the roller 5 engages with the contact a alone.

For each pair of contacts it is, therefore, possible to indicate theposition in which both contacts a, b contact with the roller 5. is asharply bounded position this is taken advantage of to make known theattainment of e. g. the center of the wave band associated with the pairof contacts.

Fig. 5 diagrammatically shows the contact device a, b, 5 and thesignalling device attended thereby, The signalling device comprises twosources of illumination 6 and I of which the source of illumination 6can give off red light, and the other source of light I can give off acomplementary color, i. e.. green light. The source or" light 6 isconnected to one end of the secondary 3 of the transformer and to the acontact of the pairs of contacts. The source of light I is connected tothe other end of the winding 6 and to the b contact of the pairs ofcontacts. The contact roller 5 is connected to the center of the winding8. Now, when the contact Since this roller 5 is connected to the lacontact alone, only the electric circuit which includes the source oflight 6 is closed. This source of light thus radiates red light. If thecontactroller 5 contacts with the I) contact alone, only the circuit forthe source of light 1 is closed. This is consequently made known byradiation of green light. If the center of a wave band is reached thecontact roller 5 engages with both contacts a, b with the result thatthe circuits of both lamps are closed and consequently both red andgreen light are radiated. If as shown in Fig. '7 the two sources ofillumination 6 and I are arranged at the back of a ground glass 9, thisglass will appear illuminated white on the front side. If tuning iseffected by means of the coarse adjustment tuning condenser C butslightly by the side of the center of the wave band either the source oflight 6 (red) or the source of light] (green) will burn. Thus, the userhas got an accurate-indication when the position of the coarseadjustment tuning device must occupy, to pass over to band spreading bymeans of the fine adjustment tuning device, is reached. Those skilled inthe art are fully aware of the manner of connecting each pair ofcontacts ab into parallel with light sources 6 and I so that as the disc4 rotates roller 5 will successively close the signal circuits asexplained in connection with Fig. 5.

In addition, according to the invention on entering into a wave band orleaving it by means of the coarse adjustment tuning device the user ofthe set may also obtain an indication. In the form of construction shownin Fig. 3 et seq., the a and 1) contacts of each pair of contacts areconstructed for this purpose in such manner that when the tuningcondenser C is tuned to one or to the other of the ends of a wave band,for example the 30 meter wave band, the contact roller 5 engages the enda or the end b, shown in Fig. 3, of the contacts a and b of the pair ofcontacts 30. In this case either the red source of light 6 or the greensource of light 'I will,

therefore, burn. At the moment when the wave band is left on one or onthe other side the contact roller 5 will therefore also leave the acontact at the end a or the b contact at the end 1; so that the sourceof light 6 or I respectively extinguishes.

What I claim is:

1. In a multi-band receiver of the type having a main reactor which iscontinuously variable for tuning the receiver through at least aplurality of high frequency bands and which is adjustable to a singlepredetermined position in each of said high frequency bands, saidpositions being diiTerent for said several bands, and an auxiliaryreactor continuously variable to tune the receiver through each of saidhigh frequency bands and for effecting band spread in each band, meansfor effecting substantially accurate adjustment of the main reactor tosaid predetermined positions and for visually indicating the same,comprising a member movable with the main reactor, a plurality of pairsof closely spaced contacts, one pair for each predetermined position,carried by said member, said contact pairs being spaced apart in thesame angular relation as the predetermined positions of the mainreactor, a normally open circuit including a visual indicatorindividually connected to each contact of said pairs, and a fixedcontact disposed in the path of the movable contacts adapted uponvarying the main reactor to successively close first one, then both andfinally the other of each oi said normally. open pairs of circuitswhereby 2. In a radio recelvingapparatus, atuningvrea actor. andacontrol shaft therefor, manually operatedrneans for actuating.saidflshaft, and means to e fiect accurate adjustment of Saddamactor.to. a desired. position and to visually indicate said. accurateadjustment and also positions adjacent thereto, said means, compris-ving amemloer in the form of a disc movable with the control shaft, apair'of spaced'contacts carried ina peripheral depression of thediscmeme 1361f, anormallyopen circuitincludinga light sourcesindividually Connected toil each of said contacts, anda relatively.fixed contact roller constructed and arranged toride on the discperiphery upon. operation-of the control shaft to successively closefirstone, then both and finally theotherwof said normally open circuitswhereby theaccurate,adjustment andrtheposition of the tunin'gfreactorone'ither side thereof are visually indicatedl 3."A multi-band radioreceiver capable. of re eewa e caption, in at least a plurality ofihighfrequency,

bands. comprising; at, least one "tunable; c including'a coarseadjustment variablefcondenself' for] continuously tuning said circuitryover said several bands, means for adjusting said tuning" condenser tothe mid-frequency of each highIrequency' band, a fine. adjustmentvariable cone denser, included in said: circuit and adjustable when, thecoarse adjustment condenser is ad-l justed to one/of the mid-frequencypositions to" effect band'spreading of said, tunable circuit to tune thesame over the corresponding high free quency band, and,meanscooperatively related with'the.adjustingfmeans for the coarse,adjust: ment condenser for giving a, visualindication upon. adjustmentof said condenser to itsmid r frequency.position,- saidmeans comprisinga fizged contact, a pairo'f contacts. movable with, the

coarse adjustment condenser andsov disposed

